Adults of all species are approximately 6 to 8 mm in length. Western corn rootworm adults are yellow with prominent black stripes on the inner and outer margins of their elytra. Northern corn rootworm adults are light green with no markings evident on elytra. Mexican corn rootworm adults range in color from green to yellow, but are most commonly dark green. Adults of this species may possess blackish stripes on the outer margin of the elytra. Southern corn rootworm adults are yellow with 6 black spots on each elytron.

Eggs:

The small eggs are tan to white and deposited in the soil.

Larvae:

The slender, white larvae are found in the soil and grow to 6 to 7 mm long. Larvae appear legless and are typically associated with plant roots.

Hosts:

Larvae of western, northern, and Mexican corn rootworms feed almost exclusively on corn roots. Adults of these species feed on pollen and plant material of many plant species. However, corn silks and pollen often are preferred. The larvae and adults of southern corn rootworm feed on many plant species.

Damage:

Larvae of all species feed on corn roots. Feeding may result in plant lodging, “goosenecking”, and yield loss. Southern corn rootworm larvae also may decrease corn plant stand by feeding on developing seedlings.

Adults feed on corn silks, leaves, and pollen. Leaf and pollen feeding does not cause economic damage, however, silk feeding can be severe enough to result in decreased pollination of corn seeds.

Phenology:

Western, northern, and Mexican corn rootworms have 1 generation per year. These species overwinter in the egg stage. Larvae are present in the spring and adults are found during the late spring through summer. Southern corn rootworm overwinter as adults and may have multiple generations each year.

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